1. Field of the Invention
This invention relates to coffee percolators, and more particularly to a temperature actuated pump control means for a coffee percolator.
2. Description of the Prior Art
Two basic types of apparatus are used for brewing coffee. Drip coffee brewing apparatus heats water to a temperature near the boiling point and then dispenses the heated water into a chamber containing coffee grounds surrounded by a filter. The heated water passes over the coffee grounds only a single time and yields coffee having a desirable flavor. The coffee percolator brews coffee in a substantially different way. Once energized the percolator virtually immediately begins pumping relatively cool water up a fountain tube and into a coffee ground receptacle containing coffee grounds. The water dispensed into the coffee ground receptacle is at first relatively cool but toward the end of the brewing cycle becomes quite warm. Coffee flavored water trickles from the perforated lower portion of the coffee ground receptacle and is mixed with the warming water in the inner chamber of the coffee percolator.
It is well known to those skilled in the art that aeration of coffee flavored water chemically alters the flavor of the coffee as it is brewed and causes it to assume an unpleasant bitter taste. In the electrically heated coffee percolators, this undesirable aeration is caused by bubbles being entrained in the heated water which is pumped up the fountain tube of the percolator and generally by the exposure of the coffee flavored water to the air as it is discharged from the upper portion of the fountain tube into the coffee ground receptacle. The continuous recirculation of the heated coffee flavored water over the coffee grounds not only increases the strength of the coffee, but also increases the bitterness of the coffee.
The drip method of coffee brewing produces coffee having a superior taste since the exposure of the liquid coffee to air is reduced to an absolute minimum. The inherent disadvantage of drip brewing apparatus resides in their high purchase price and their failure to fully extract all the flavor present in the coffee grounds since heated water is passed over the grounds only a single time.
A number of attempts have been made in the past to modify a percolator having a heat powered pump into an apparatus capable of brewing coffee by the drip method.
U.S. Pat. No. 1,582,685 (Pence) discloses a dual chambered coffee percolator having a steam powered water pump which is thermostatically controlled. A thermostatically actuated plug closes off an aperture in the lower portion of the fountain tube element of the pump until the water in the lower chamber of the percolator has reached a predetermined temperature. Upon reaching that temperature the thermostat removes the plug from the fountain tube and the pump commences operation, causing heated water to be dispensed through the raw coffee into the upper chamber of the percolator.
The difficulty with the Pence apparatus is that it performs a function which is accomplished in a much more satisfactory manner by the present day drip coffee percolators. The Pence apparatus is expensive in that it contains a number of chambers and a relatively complicated, non-replaceable pump control means. The Pence percolator similarly circulates the water only a single time over the raw coffee in the coffee basket.
U.S. Pat. No. 2,046,710 (Umstott) discloses a coffee percolator similar to that taught by Pence. The Unstott percolator is designed to brew coffee by the drip method and includes a thermostatically actuated percolator pump and a dual chambered percolator container.
U.S. Pat. No. 1,743,342 (Halstead) discloses a conventional coffee percolator having an improved valve apparatus which causes the coffee pump to be intermittently actuated as the temperature of the water in a small compartment at the lower end of the pump is heated to a temperature near its boiling point. As the water in the small pump chamber is converted to steam, a valve is closed and a pulse of hot water is pumped up the fountain tube and over the coffee grounds. The inherent disadvantage of this apparatus is that its long percolating cycle continuously aerates the coffee flavored water and gives the coffee a bitter flavor.
Other patents disclosing various other types of coffee brewing apparatus are disclosed in the following U.S. Pat. Nos.: 1,995,081 (Sommers); 1,696,451 (Rankin); 2,742,927 (Frumet); 2,975,723 (Andrews); 3,103,872 (Kircher); and 3,856,435 (Ballard).